Coal burning device



Sept. 26, 1933; R, E BRESSLER 1,928,166

COAL BURNING DEVICE Filed. Aug. l1, 1930 @65mg ra-@v Patented Sept. 26, 1933 UNITED STATES PATENT OFFICE 1,928,166 COAL BURNING DEVICE Robert E. Bressler, Oregon, lll. Application ugust 11, 1930. Serial No. 474,327

1 Claim. (Cl. 110-47) This invention relates to coal burning devices of the underfeed type and has for its object to provide a new and improved device of this description.

When coal, for example, is fed to an underfeed retort from below, with the fire above, the coal is heated and taris produced, and other more or less .volatile ingredients in the coal are partly freed, thereby forming a sticky mass which packs very readily. One of the objects of the present invention is to provide means for preventing the packing of this mass and maintaining a loose mass in the retort.

The invention has as a further object to provide an even distribution of the coal in the retort.

The invention has as a further object to prevent the coal from piling up in the back of the retort.

The invention has other objects which are more particularly pointed out in the accompanying description.

Referring now to the drawing, Fig. 1 is a sectional view through one form of device embodying the invention.

Fig. 2 is a sectional of Fig. l.` A

Fig. 3 is a view similar to Fig. 1 showing a modified construction.

The form of invention disclosed in the accompanying drawing illustrates an underfeed retort having an upper twyer section with open top and bottom and with upwardly diverging sides and ends, the twyer section being defined by bars 7 separated by open spaces or twyers 8 for air passage.

A magazine or supply hopper 1 is arranged to discharge into a conduit 3 for delivery of fuel to the retort. Extending through the conduit and underneath the twyer section is a shaft 4 driven by a motor 5 through any suitable form of speed reduction gearing indicated generally at 6. In the illustration of the invention in Fig. 1 the conduit 3 is extended beyond the opposite portion of the open bottom of the retort to provide a recess or pocket 10 into which the end of the shaft extends. Within the conduit 3 is a spiral screw or conveyor flightv 2 which terminates adjacent one marg' 1=` the open bottom of the twyer section. Another flight 9 is secured to the shaft 4 and lies within the pocket or recess 10 beyond the opposite margin of the bottom opening ofthe twyer section, that is, opposite to the margin adjacent which the flight 2 terminates. Another flight 11 is secured to the shaft 4 underneath or below the open bottom of the retort.

view taken on line 2 2 A guard 12 is disposed above the flight 11 so as to prevent feeding contact of the flight 11 with fuel within the retort when no fuel is being delivered to the retort by the conveyor. y

The flights 2, 11 and 9 are of different pitch andV so designed that flight 11 will move fuel or coal in the rdirection imparted to the coal by the flight 2 but at a slower speed, so that coal will pile up between the flights 2 and 11 and thus be forced into the twyer section.

The flight 9 is of different pitch from the flight 2 and flight 11 and, in Figs. 1 and 3, is illustrated as being a reverse pitch from that of the flight 2. The function of the flight 9 is to move coal in opposition to the direction of movement imparted thereto by the flights 2 and 11 and thus aid in piling up the fuel between these flights for forcing the fuel into the twyer section.

Such fuel as is advanced by the flight 11 towards the flight 9 will be opposed by action of the flight 9 and forced upwardly into the twyer section through the openvbottom of the same.

Since the flight 11\ cannot feed fuel or coal as much as is fed by the flight 2, in a given time, a portion of the coal will be piled up between these flights and thus forced into the twyer section.

In the event that the hopper 1 and conduit 3 are emptied of fuel, but the conveyor is still rotating, the guard 12 over the flight 11 will prevent contact of the coal fed by this flight with the coal thereabove in the twyer section. In like manner because of the shielding of the flights 2 and 9 and the particular construction :described these flights do not have feeding contacts with the fuel within the twyer section; that is, when no coal is being sent to the twyer section. Consequently, the feeding elements will not churn the fuel in the twyer section or mingle unburned with burning fuel, thus eliminating the objectionable churning resulting in such forms of underfeed stokers. where, in the absence of fuel being fed, the conveyors churn the fuel within the twyer section thereby mixing unburned with burning fuel and convey the live, hot coal from the top of the twyer section down to the bottom.

The apparatus herein disclosed feeds the fuel evenly to the twyer section and prevents churning of the fuel within the twyer section when no fuel is being fed to the same.

Figure l illustrates a construction wherein a single intermediate flight l1 is interposed between the main flight 2 and the flight 9 within the conduit recess.

In Figure 3 an arrangement is illustrated where there are two intermediate flights between the 2.5 \dicated at 12a in Figs.

main night 2 and the night 9 within the recess 10. In the arrangement illustrated in Figure 3 an intermediate night l1 is provided as well as another intermediate night 13. These nights are of different pitch from each other and also from the nights 2 and 9, the purpose being to force the fuel upwardly into the twyer section by the differential feeding action of the spaced nights.

The night 11 is protected by a cover or guard l2, While the flight 13 is shielded by a guard 14. In this construction, like the construction of Figure 1, the main flight 2 is shielded from the fuel within the twyer section by reason of the fact that the night 2 terminates adjacent one margin of the open bottom of the twyer section, and in like manner the flight 9 is shielded from being in contact with the fuel in the twyer section by reason of the fact that this night is within a recess or pocket 10.

The reduction of speed of feeding by the intermediate flights 11 and 13 may be accomplished by decreasing the pitch of these nights or may be secured by maintaining the pitch the same and providing an obstructing device such as that in- 1 and 2, which is there illustrated as projecting in front of the flight l1 in the direction of movement of the fuel. The obstructing device 12a obstructs or limits the feed of material to the intermediate flights 11, thus cutting down the material advanced by these nights towards the rear end of the conduit 3.

The arrangement of Fig. 3 is such that the pitch of the night 13 is less than the pitch of the night 11, so as to cause piling up of some fuel between these flights for entering into the retort. The action of the night 9 is to oppose advance of fuel by the night 13, thus causing piling up of the fuel for forcing it into the twyer section through the open bottom of the same.

I claim:

An underfeed Stoker comprising a retort having an imperforate bottom member and an upper twyer section, a fuel feed conduit extending from said bottom member, a fuel feed hopper ccmmunicating with said conduit, a screw conveyor shaft extending through said conduit and below said twyer section longitudinally of and adjacent the bottom of said member, said shaft having thereon axially spaced conveyor nights of different pitches, the nights of maximum pitch being within the conduit and terminating at the discharge end thereof, another conveyor night being positioned within the retort below the twyer section, a guard having a horizontal portion and a depending portion overlying said other conveyor night, the horizontal portion entirely overlying said other conveyor night and the depending portion extending downwardly to said shaft at the' fuel receiving end of said other conveyor night thereby shielding said night from coming in feeding contact with the fuel in the twyer section when no fuel is being fed thereto and preventing churning and a partial circulation of the burned and unburned fuel.

, ROBERT E. BRESSLER. 

